1. Field of the Invention
The present invention relates to a contaminated fluid recovery apparatus for decontaminating a contaminated fluid in which chips, fine sludge, etc., are mixed, for example.
2. Description of the Related Art
A machine tool or the like for machining, such as cutting, grinding, etc., uses a fluid such as a coolant for cooling a workpiece. This fluid is mixed with foreign matter, such as chips (shavings) produced by machining, fine sludge, etc. In order to reuse the contaminated fluid that contains the chips, sludge, etc., a contaminated fluid recovery apparatus is used to remove the chips, sludge, etc., from the contaminated fluid.
The inventors hereof have long been developing contaminated fluid recovery apparatuses. In consequence, they have succeeded in developing a high-performance contaminated fluid recovery apparatus that combines a conveyor and a sludge removal mechanism provided with a magnetic drum, as described in Jpn. Pat. Appln. KOKAI Publication No. 2005-66820, for example.
The sludge removal mechanism includes the magnetic drum that is located at a circulating section (overflow section) near the fluid surface of a dirty tank. Fine magnetic sludge in a contaminated fluid is attracted to the outer peripheral surface of the magnetic drum. The conveyor is provided with scrapers. Relatively large chips and the like that are deposited on the bottom of the dirty tank are scraped out by the scrapers toward an exit section outside the dirty tank.
Some contaminated fluids may contain ultrafine particles, such as very fine carbon particles. While the contaminated fluid recovery apparatus is operating, these ultrafine particles tend to adhere to fine air bubbles and the like mixed in the contaminated fluid, proceed toward the fluid surface of the dirty tank, and float for hours on the fluid surface. If the sludge removal mechanism is located at the circulating section (overflow section) near the fluid surface of the dirty tank, the ultrafine particles that exist near the fluid surface inevitably flow into the side of a clean tank through the circulating section.
Even if these ultrafine particles get into the clean tank, the contaminated fluid recovery apparatus can exhibit high performance without any particular practical problem. As higher specifications will be required of the contaminated fluid recovery apparatuses in the future, however, there will possibly be a demand for contaminated fluid recovery apparatuses that can capture smaller ultrafine particles.